Abstract
In this work, lyophilization and acid treatments were proposed as simple alternatives to defiber sepiolite samples, without affecting their length, in order to be applicable at industrial scale. Although it contains carbonates, the main remarkable feature of this clay mineral is its high crystalline development, reaching fiber lengths around 8cm. Proposed alternatives were analyzed comparatively, evaluating mainly the defibering effect. The influence of lyophilization and acid treatments on sepiolite structure and purity was qualitatively studied based on mineral characterization, electronic and optical microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. Results show that acid treatment allowed sepiolite purification by removing carbonates as well as the reduction of fiber length. Lyophilization demonstrated to be an effective defibering process that allowed obtaining individualized fiber from bundle disaggregation, without affecting sepiolite length and flexibility.
Highlights
Clays and clay minerals have demonstrated to be interesting materials due to their high adsorption capability, colloidal properties as well as the possibility of tailoring their surface characteristics to provide specific solutions for a wide variety of industrial applications (Jones and Galán, 1988)
Lyophilization and acid treatments were proposed as simple alternatives to defiber sepiolite samples, without affecting their length, in order to be applicable at industrial scale
Results show that acid treatment allowed sepiolite purification by removing carbonates as well as the reduction of fiber length
Summary
Clays and clay minerals have demonstrated to be interesting materials due to their high adsorption capability, colloidal properties as well as the possibility of tailoring their surface characteristics to provide specific solutions for a wide variety of industrial applications (Jones and Galán, 1988). Since clays are very abundant and naturally occurring, they are relatively cheap and environmentally friendly materials with good properties, which makes them very attractive in the academic and industrial field. Sepiolite is a clay mineral used in a wide range of technological applications. Each structural block is composed by two-dimensional tetrahedral silica sheet and a central magnesium octahedral one. Tetrahedral sheets are inverted every six units, determining a regular
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